directly add tests over the trailing slash.

src/SMAPI.Tests/Core/AssetNameTests.cs

@@ -265,6 +265,26 @@ namespace SMAPI.Tests.Core
             return name.StartsWith(otherAssetName, allowPartialWord: true, allowSubfolder: allowSubfolder);
         }
 
+        // the enumerator strips the trailing path seperator
+        // so each of these cases has to be handled on each branch.
+        [TestCase("Mods/SomeMod", "Mods/", false, ExpectedResult = true)]
+        [TestCase("Mods/SomeMod", "Mods", false, ExpectedResult = false)]
+        [TestCase("Mods/Jasper/Data", "Mods/Jas/", false, ExpectedResult = false)]
+        [TestCase("Mods/Jasper/Data", "Mods/Jas", false, ExpectedResult = false)]
+        [TestCase("Mods/Jas", "Mods/Jas/", false, ExpectedResult = false)]
+        [TestCase("Mods/Jas", "Mods/Jas", false, ExpectedResult = true)]
+        public bool StartsWith_PrefixHasSeperator(string mainAssetName, string otherAssetName, bool allowSubfolder)
+        {
+            // arrange
+            mainAssetName = PathUtilities.NormalizeAssetName(mainAssetName);
+
+            // act
+            AssetName name = AssetName.Parse(mainAssetName, _ => null);
+
+            // assert value
+            return name.StartsWith(otherAssetName, allowPartialWord: true, allowSubfolder: allowSubfolder);
+        }
+
 
         /****
         ** GetHashCode

src/SMAPI/Framework/Content/AssetName.cs

@@ -163,7 +163,7 @@ namespace StardewModdingAPI.Framework.Content
                         return false;
 
                     // match if subfolder paths are fine (e.g. prefix 'Data/Events' with target 'Data/Events/Beach')
-                    return allowSubfolder;
+                    return allowSubfolder || (pathSeparators.Contains(trimmedPrefix[^1]) && curParts.Remainder.Length == 0);
                 }
 
                 // previous segments matched exactly and both reached the end